Copyright: Getmapping plc 2005

What is ‘special’ about Rhosneigr Reefs SSSI?

As well as the features listed above, Rhosneigr Reefs SSSI has other habitats that are essential to the maintenance of the special wildlife interest. These include intertidal rock experiencing a range of wave exposure conditions, from exposed through to sheltered, intertidal gravels and sands and maritime hard cliffs. This diversity of habitats similarly supports a wide range of species and these too are a key component of the special interest of the site. Unless specified below, management of this site should aim to look after these habitats as well as the listed features of interest.

What do we want Rhosneigr Reefs to look like?

Species-rich tidal rockpools. Within the reefs there are sixteen rockpools with a rich diversity of plants and animals, including red and green seaweeds, crabs, starfish and a variety of fish species. The presence and diversity of these communities should be maintained, subject to natural variation.

Species-rich communities found underneath boulders and rocky overhangs A similar diversity of plants and animals are found underneath boulders on the shore and on the rock overhangs, including red seaweeds, sea mats, hydroids (sea firs), sponges and sea squirts. Five distinct overhang and under-boulder communities have been recorded across the shore. The presence and diversity of these communities should be maintained, subject to natural variation.

Species-rich tidal channels with cobbles and mixed sediment.

This site has a series of tidal channels, some of which remain underwater at low tide. The bottom of these channels consists of cobbles and mixed substrate. Sheltered conditions in these channels have allowed the development of a rich flora and fauna characterised by thick growths of wracks and kelps, with an understorey of red and green seaweeds supporting a variety of animal species.

Species of red seaweed and crabs that are rare in North Wales. Two species of red seaweed (Hypoglossum hypoglossoides and Laurencia obtusata) and two species of crab (Liocarcinus arcuatus (, a swimming crab and Pisa tetraodon, a spider crab), have been found living on the shore here.

What management is needed on Rhosneigr Reefs SSSI and why?

Although Rhosneigr Reefs is an excellent place for wildlife it will only remain so if the necessary management continues. CCW’s aim is to work with you to ensure that this management is carried out.

What does this mean in practice?

There are many factors that could damage the special features at Rhosneigr Reefs if they are not properly managed. These are the ones we regard as most important:

Natural change: Communities on this shore are subject to variations in distribution, size and composition, caused by natural events such as tides, waves and weather.

Boat moorings: Boat mooring chains can damage some soft sediment communities on this shore. Existing moorings do not appear to pose a threat to the scientific interest of this site. Further moorings, if required, should be placed in the least sensitive areas in consultation with CCW and the local authority. The use of buoyant (polypropylene) risers may also limit the impact of moorings.

Coastal protection: Movement of sediment, including erosion and deposition, is a natural process that is integral to the quality of the shore. Works that might disrupt natural movement of sand and silt, or change the movement of water, such as slipways, groynes or other coast defence structures should be resisted to protect the integrity of the site. Issues of overriding public interest or safety will be considered on merit.

Pollution and sewage: Marine biological communities are vulnerable to pollution such as oil spills, sewage outfalls and fertiliser run-off from farmland, as well as changes in turbidity (water clarity). Precautionary measures are encouraged by CCW working with landowners, occupiers and other agencies, e.g. the Environment Agency.

Recreational Fishing/Angling: There is no evidence that recreational fishing (angling, shrimping etc.) causes significant damage to the marine communities of special interest on this site. However, under-boulder communities, in particular, would be vulnerable to high levels of boulder turning by peeler crab (bait) collectors. CCW encourages good practice as outlined in the ‘Conservation Code for Anglers’.

Other recreational activities: Trampling and off-road vehicles can have a detrimental impact on shore communities. It is not thought that recreational use of the shore is detrimental to the marine features at present. If trampling or off-road vehicles are found to be damaging the site in future, CCW will work with owners, occupiers, interested parties and other agencies (police and Local Authorities) to minimise disturbance to important features.

Species collection / removal: Disturbance through collection of specimens from rockpools for educational, scientific, commercial or recreational purposes (e.g. “rockpooling”) could threaten the rockpool and underboulder communities characteristic of this site, if occurring at high levels. However, it is not thought that such activities are detrimental to the marine features at present. If such activities are found to be damaging the site in future, CCW will work with owners, occupiers, interested parties and other agencies (police and Local Authorities) to minimise disturbance to important features.

Wire weed or Jap Weed and other invasive or alien species: This invasive brown seaweed, which may reduce the diversity of marine life in rock pools such as those present in this site, has been found. Its growth will be monitored along with any impact on the features of special interest. Attempts to eradicate Wire Weed from other sites, such as Strangford Lough in Northern Ireland have proved difficult. With a changing global climate and human transportation of species, other invasive or alien species may be found more commonly in the future around our coastline. These may have the potential to impact the marine features of this site. However, CCW would work with owner/occupiers and partners to seek a viable solution should Wire Weed or other invasive species be deemed to be a threat to the features of the site.


Our knowledge of wildlife is far from complete. It is possible that new features of value may appear and new management issues may arise in the future, whilst other issues may disappear. This statement is written with the best information we have now, but may have to change in the future as our understanding improves. Any information you can provide on the wildlife of your site, its management and its conservation would be much appreciated.

If you would like to discuss any aspect of your SSSI, or have any concerns about your SSSI, please contact your local CCW office.

Your local office is;

Cyngor Cefn Gwlad Cymru/Countryside Council for Wales

North Region

Llys y Bont,

Ffordd y Parc,

Parc Menai,


Gwynedd, LL57 4BN,

Telephone: 01248 672500